Spinal Muscular Atrophy (SMA) Biomarkers Study in the Immediate Postnatal Period of Development

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Spinal muscular atrophy (SMA) is the leading genetic cause of death of infants. Strong preclinical evidence suggests that effective therapy must be delivered as early as possible to prevent progression of the disease. The primary study objective will be to identify prognostic and surrogate biomarkers of disease progression that will facilitate the execution of therapeutic SMA clinical trials in infants.

Condition or disease

Spinal Muscular Atrophy (SMA)

Detailed Description:

Aim 1. To establish the validity of putative physiological SMA biomarkers in the immediate postnatal period. A longitudinal, natural history examination of physiological markers of muscle innervation will be performed in healthy and SMA infants. The first week of life is the ideal first time point, with visits occurring at scheduled visits up to the age two. Compound motor action potential (CMAP) amplitude and electrical impedance myography (EIM) will be examined and will be correlated with motor function. Each of these is associated with muscle innervation and provides information on the number and function of lower motor neurons in the spinal cord, the cellular target of SMA therapeutic interventions. This trial will establish the natural history of these putative SMA biomarkers as the disease evolves in affected infants. Moreover, our approach will allow for measurements in pre-symptomatic and early symptomatic subjects and determine their predictive value.

Aim 2. To establish the validity of putative molecular SMA biomarkers in the immediate postnatal period. Survival Motor Neuron (SMN2) copy number is a valid, predictive molecular SMA biomarker; however, it is fixed, and therefore not useful as a biomarker of clinical progression or response to therapy. SMN messenger Ribonucleic acid (mRNA) ( and protein expression is variable in different cell types and, in mice, naturally decreases with age postnatally. In this study, SMN expression levels will be measured longitudinally in SMA patients and controls. Additional putative molecular SMA markers that have been identified to correlate with motor function will be determined in an effort to distinguish between predictive markers that change prior to development of weakness and those that change as a consequence of weakness.

Describe & compare the distribution of motor function assessments over the first two years of life in SMA vs. healthy control infants.

The TIMPSI is used to assess the postural and selective control of movement typically used by infants younger than 5 months. The TIMPSI scores were related to an infant's ability to reach. The TIMPSI is a 29-item evaluation that contains 3 item sets: a Screening set, an Easy set, and a Hard set. The Screening set consists of 11 items from the TIMP, each with a 5- to 7-point rating scale; the Easy set has 6 items with 5- or 6-point rating scales and 4 dichotomously scored items; the Hard set has 8 items, 3 with 5-point rating scales and 5 items that are scored dichotomously. The Total score is derived from all subset scores and is the sum of those subset scores. The final score could range from 0 to 99 points. The higher the score the better the functional ability of the participant. Linear mixed effects models were used for analyses.

The TIMPSI motor function testing was done during all of the study visits knowing that the healthy controls would eventually ceiling out. The study design allowed for secondary motor function tests based on the score of the TIMPSI. If infants scored a 41 or above on the TIMPSI they would be tested with the AIMS. If they were below they were tested with the CHOP-INTEND. The CHOP-INTEND is a reliable and validated, comprehensive assessment of the postural and selective control of movement needed by infants. It is a clinician-rated questionnaire developed to assess motor skill in spinal muscular atrophy type I. The 16 items are scored from 0 to 4. The global score ranges from 0 to 64, a higher score indicating better motor skills.(Finkel, McDermott, 2014). All healthy controls based upon scores at 6 months moved on to the AIMS test, therefore no healthy controls completed the CHOP-INTEND. Linear mixed effects models were used for analyses of Motor function outcome data.

The reason that the number of infants differ from those in participant flow is based upon the protocol. The selection of which secondary test to perform depended upon the score of the TIMPSI that was performed. TIMPSI <41, do CHOP-NTEND. TIMPSI > 41, do AIMS.

The AIMS incorporates the neuromaturational concept and the dynamical systems theory and is used to measure gross motor maturation of infants from birth through the age of independent walking (Piper, Pinnell et al. 1992, Piper, Darrah et al 1994). In the AIMS, the impact of neurological components on motor development is reflected by a sequence of motor skills, which are used as the basis of assessment. The AIMS consists of 58 items, including 4 positions: prone (21 items), supine (9 items), sitting (12 items) & standing(16 items). The highest score available is 58. The higher the score the better the functional ability of the participant.

Describe and compare the distribution of the putative physiological and molecular biomarkers over the first two years of life in SMA vs. healthy control infants.

Maximum ulnar CMAP amplitude and area will be obtained by recording from the abductor digitiminimi muscle following ulnar nerve stimulation at the wrist. All electrophysiologic testing will be performed by certified electromyographers experienced in the assessment of pediatric patients. Maximum values for both negative peak (NP) amplitude and NP area will be obtained. No medications will be used.

This test is done routinely in this population. Pediatric electrodes and each site's standard electromyograph devices will be utilized. The test, while not considered to be painful, may cause some discomfort similar to a static electric shock. Infants may whimper or cry due to the surprise of the shock. Each shock lasts approximately 0.1 millisecond. The testing duration is expected to be approximately 30 seconds.

Molecular Biomarkers- mRNA [ Time Frame: Up to 24 months ]

Describe and compare the distribution of the putative physiological and molecular biomarkers over the first two years of life in SMA vs. healthy control infants.

Describe and compare the distribution of the putative physiological and molecular biomarkers over the first two years of life in SMA vs. healthy control infants.

Correlation of Biomarkers With Motor Function Tests for SMA Subjects- CMAP [ Time Frame: up to 24 months ]

In these analyses motor function score was the outcome measure. Correlation was defined as the estimated mean increase per a one unit increase in the biomarker under consideration. A linear mixed effects model was used to estimate the correlation between the biomarker and motor function score. Separate models were used for the TIMPSI and CHOP-INTEND. In the CHOP-INTEND analyses, correlations were not estimable for the 18 and 24 month visits.

Correlation of Biomarkers With Motor Function Tests for SMA Subjects- mRNA [ Time Frame: up to 24 months ]

In these analyses motor function score was the outcome measure. Correlation was defined as the estimated mean increase per a one unit increase in the biomarker under consideration. A linear mixed effects model was used to estimate the correlation between the biomarker and motor function score. Separate models were used for the TIMPSI and CHOP-INTEND.

Correlation of Biomarkers With Motor Function Tests for SMA Subjects- SMN Protein [ Time Frame: up to 24 months ]

In these analyses motor function score was the outcome measure. Correlation was defined as the estimated mean increase per a one unit increase in the biomarker under consideration. A linear mixed effects model was used to estimate the correlation between the biomarker and motor function score. Separate models were used for the TIMPSI and CHOP-INTEND. In the CHOP-INTEND analyses, the correlation at the 24 month visit was not estimable.

Correlation of Biomarkers With Motor Function Tests for SMA Subjects- Weight [ Time Frame: up to 24 months ]

In these analyses motor function score was the outcome measure. Correlation was defined as the estimated mean increase per a one unit increase in the biomarker under consideration. A linear mixed effects model was used to estimate the correlation between the biomarker and motor function score. Separate models were used for the TIMPSI and CHOP-INTEND.

Correlation of Biomarkers With Motor Function Tests for Healthy Control Subjects- CMAP [ Time Frame: up to 24 months ]

In these analyses motor function score was the outcome measure. Correlation was defined as the estimated mean increase per a one unit increase in the biomarker under consideration. A linear mixed effects model was used to estimate the correlation between the biomarker and motor function score. Separate models were used for the TIMPSI and AIMS.

Correlation of Biomarkers With Motor Function Tests for Healthy Control Subjects- mRNA [ Time Frame: up to 24 months ]

In these analyses motor function score was the outcome measure. Correlation was defined as the estimated mean increase per a one unit increase in the biomarker under consideration. A linear mixed effects model was used to estimate the correlation between the biomarker and motor function score. Separate models were used for the TIMPSI and AIMS.

Correlation of Biomarkers With Motor Function Tests for Healthy Control Subjects- Weight [ Time Frame: up to 24 months ]

In these analyses motor function score was the outcome measure. Correlation was defined as the estimated mean increase per a one unit increase in the biomarker under consideration. A linear mixed effects model was used to estimate the correlation between the biomarker and motor function score. Separate models were used for the TIMPSI and AIMS.

Secondary Outcome Measures :

Biomarker Prediction of Risk of Death [ Time Frame: Up to 24 months ]

Examine whether any of the motor function assessments, putative physiological, or molecular biomarkers predict risk of death in the SMA cohort. Proportional hazards regression models used to determine if motor function scores, mRNA, and protein levels predict death in SMA subjects. Considered each predictor separately modeled as a time-varying covariate (predictor values were allowed to vary as time to death was assessed).

Describe and compare the distribution of motor function assessments over the first two years of life in SMA subjects with SMN copy number = 2 versus healthy control infants.

The TIMPSI is used to assess the postural and selective control of movement typically used by infants younger than 5 months. The TIMPSI scores were related to an infant's ability to reach. The TIMPSI is a 29-item evaluation that contains 3 item sets: a Screening set, an Easy set, and a Hard set. The Screening set consists of 11 items from the TIMP, each with a 5- to 7-point rating scale; the Easy set has 6 items with 5- or 6-point rating scales and 4 dichotomously scored items; the Hard set has 8 items, 3 with 5-point rating scales and 5 items that are scored dichotomously. The Total score is derived from all subset scores and is the sum of those subset scores. The final score could range from 0 to 99 points. The higher the score the better the functional ability of the participant.

Describe and compare the distribution of motor function assessments over the first two years of life in SMA subjects with SMN copy number = 2 versus healthy control infants.

The CHOP-INTEND is a reliable and validated, comprehensive assessment of the postural and selective control of movement needed by infants. It is a clinician-rated questionnaire developed to assess motor skill in spinal muscular atrophy type I. The 16 items are scored from 0 to 4. The global score ranges from 0 to 64, a higher score indicating better motor skills.(Finkel, McDermott, 2014).

Describe and compare the distribution of the putative physiological and molecular biomarkers over the first two years of life in SMA2 vs. healthy control infants.

Maximum ulnar CMAP amplitude and area will be obtained by recording from the abductor digitiminimi muscle following ulnar nerve stimulation at the wrist. All electrophysiologic testing will be performed by certified electromyographers experienced in the assessment of pediatric patients. Maximum values for both negative peak (NP) amplitude and NP area will be obtained. No medications will be used.

This test is done routinely in this population. Pediatric electrodes and each site's standard electromyograph devices will be utilized. The test, while not considered to be painful, may cause some discomfort similar to a static electric shock. Infants may whimper or cry due to the surprise of the shock. Each shock lasts approximately 0.1 millisecond. The testing duration is expected to be approximately 30 seconds.

Examine the correlation between each of the putative physiological and molecular biomarkers with the TIMPSI and CHOP-INTEND over the first two years of life in SMA (SMN = 2). All estimated correlations are the same at each study visit.

Examine the correlation between each of the putative physiological and molecular biomarkers with the TIMPSI and CHOP-INTEND over the first two years of life in SMA (SMN = 2). All estimated correlations are the same at each study visit.

Examine the correlation between each of the putative physiological and molecular biomarkers with the TIMPSI and CHOP-INTEND over the first two years of life in SMA (SMN = 2). All estimated correlations are the same at each study visit.

Examine the correlation between each of the putative physiological and molecular biomarkers with the TIMPSI and CHOP-INTEND over the first two years of life in SMA (SMN = 2). All estimated correlations are the same at each study visit.

Biospecimen Retention: Samples With DNA

Absolute quantification of full length survival motor neuron (SMN) transcripts will be performed. The SMN1 and SMN2 transcripts will be measured in a multiplex reaction and SMN-del7 will be quantified separately. Droplet digital PCR will be used to determine SMN levels to further increase reliability and reduce variance in the SMN mRNA level determination. SMN protein in PBMCs SMN cell-based immunoassays will be performed. This assay is performed using a single monoclonal antibody for SMN and does not involve the disruption of cells. From the same PBMC sample, a commercially available SMN ELISA will also be performed according to the manufacturer's instructions. The B for SMA pilot study identified over 100 protein analytes that significantly correlated with motor function in SMA patients compared to controls.

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Layout table for eligibility information

Ages Eligible for Study:

up to 6 Months (Child)

Sexes Eligible for Study:

All

Accepts Healthy Volunteers:

Yes

Sampling Method:

Non-Probability Sample

Study Population

Fifty four (54) volunteers will be enrolled at 15 NeuroNEXT Network centers. Any volunteer who signs an informed consent form and has blood collected for the study is considered enrolled.

Recruitment will be coordinated nationally through the Families of SMA Patient Network and NeuroNEXT who will help with the following:

Identifying infants diagnosed genetically with SMA because of a clinical suspicion prior to 6 months of age.

Publicize the project to raise awareness in medical and non-medical communities.

Any normal infant may enroll in this study.

Criteria

Inclusion Criteria:

All infants will be between 0-6 months of age at the time of enrollment. Parents or guardians of the enrolled infants must sign an informed consent form prior to any study procedure being performed.

The infants with SMA must have already had a positive DNA test outside of the study to qualify for enrollment. An infant with SMA can have any number of SMN2 gene copies. Knowledge of the number of SMN2 gene copies prior to enrollment is not required.

Healthy control infants who meet the following criteria will be enrolled:

Birth between 36 and 42 weeks inclusive of gestation

Siblings of children with SMA must have had prior SMA genetic testing completed con-firming the infant is a healthy control

Principal investigator feels the family/infant is able and willing to comply with study procedures

Parent or guardian able to give informed consent

SMA infants who meet the following criteria will be enrolled:

Birth between 36 and 42 weeks inclusive of gestation

Positive SMN1 gene mutation/deletion

Principal investigator feels the family/infant is able and willing to comply with study procedures

Parent or guardian able to give informed consent

Exclusion Criteria:

Use of any putative therapy intended to increase the amount of SMN protein in cells

Enrollment in an SMA therapeutic trial at the time of enrollment in the SMA biomarker study

Have a systemic illness requiring ongoing treatment, such as pneumonia

Clinically significant abnormal findings (as determined by the investigator) on the physical examination or medical history (including history of tracheostomy tubes and ventilator-dependency)

Dependency upon non-invasive ventilatory support (ie: BiPAP) for more than 12 hours/day